Solar energy is a pollution-free, safe renewable energy, and there is a considerable development potential. In particular, it is the current trend of energy conservation that solar cells are integrated into building materials. For instance, solar photovoltaic panels are utilized to replace the roof materials, exterior walls, or building glasses of constructions. However, because the voltage generated by a single solar photovoltaic panel is very small, a plurality of solar photovoltaic panels is often connected serially via the junction boxes for forming a larger voltage to be used.
The conventional junction box is a small box which includes a plurality of Schottky diodes and two external cables with a cathode connector and an anode connector. A conventional solar photovoltaic system is composed of a plurality of solar photovoltaic panels, a high-voltage breaker and an inverter, in which the solar photovoltaic panels are connected in serial connections via anode and cathode connectors of the junction boxes to form a terminal voltage of several hundred volts.
However, once an exception or a fire accident has occurred in the conventional solar photovoltaic system, the DC high-voltage power becomes a difficult problem to put out a fire because the continuously DC high-voltage power under natural sunshine results in death or injury to a fireman due to an electric shock thereof.
For instance, a solar energy system with N solar photovoltaic panels has N+1 electrical access points that the anode connector is connected to the cathode connector. In order to avoid that the DC high voltage occurs at any electrical access points, the best way is to disconnect all the N+1 electrical access points. However, when a fire occurs, it is indeed difficult to disconnect a large number of the electrical access points safely and quickly for implementing a fire fighting. Currently, the only way is to isolate it from other combustibles and then leave the fire to burn the solar photovoltaic panels out, but the fire on the roof may burn into the building to cause serious damage.
In the field of electric vehicles, the power system has also a number of battery cells connected in serial connections for supplying power to the vehicle. When a vehicle failure or overheat occurs in the vehicle, the vehicle on fire often occurs. At this point, the traditional way of the fire fighting will also have the same problem of the electric shock.
Therefore, there is a significant need for providing junction boxes and a power system using the junction boxes, which makes each junction box of the power supply unit de-serialize when a fire occurs.